> For the complete documentation index, see [llms.txt](https://chembl.gitbook.io/unichem/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://chembl.gitbook.io/unichem/web-application/connectivity-search.md). # Connectivity Search Find compounds and its sources by its InChI connectivity layers, i.e., formula, connections, H atoms and charge layers of the InChI. Similar to the compound search, compounds to compare connectivity with can be looked up using InChI, InChI Key, a source compound ID or a Unique Compound ID (UCI) {% hint style="warning" %} The image representation in the Searched Compound card is an approximated depiction of the found molecule. It might not represent exactly the found compound. For a better image of the compound please follow the link to one of the found sources. {% endhint %} ### InChI and InChIKey Find the sources linked to the [IUPAC international chemical identifier ](https://iupac.org/who-we-are/divisions/division-details/inchi/)for your compound or its hashed InChI form. ### Source Compound ID Compounds can be found by the ID assigned on a source database, simply select the Source of the compound and in the box right next to the selector enter the ID for that particular compound in the given Source. ### UniChEM Identifier (UCI) The UCI (UniChEM Identifier) is the number we use to identify a distinct compound with its linked sources in our database. --- # Agent Instructions This documentation is published with GitBook. GitBook is the documentation platform designed so that both humans and AI agents can read, navigate, and reason over technical content effectively. Learn more at gitbook.com. ## Querying This Documentation If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question. Perform an HTTP GET request on the current page URL with the `ask` query parameter, and the optional `goal` query parameter: ``` GET https://chembl.gitbook.io/unichem/web-application/connectivity-search.md?ask=&goal= ``` `ask` is the immediate question: it should be specific, self-contained, and written in natural language. `goal` is optional and describes the broader end goal you are ultimately trying to accomplish on behalf of the user. GitBook uses it to tailor the answer towards what is most useful for that goal. The response will contain a direct answer to the question and relevant excerpts and sources from the documentation. Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.